Networking devices - Which and why?
I’m writing this post as I work through the course Introduction to Computer Networks summarizing the commonly used devices on a network and their uses
Hub
A Hub is used to connect devices together within a network. It is a Layer 1 device and operates by repeating any messages it receives on all its ports. This makes a Hub very inefficient and introduces congestion within the network
Switch
A Switch is used to connect devices together within a network. It is a Layer 2 device and uses the MAC address contained within a packet to decide which port to redirect it on.
A switch retains a mapping of its Port and the MAC address of the host connected to that Port. When it has to forward a message within the network it refers this mapping and forwards the message only to the relevant Port.
A switch is capable of forwarding a message to all the ports if needed as in the case of a Broadcast message
If Switch A is connected to Switch B on one of its Ports, Switch A can store multiple MAC Addresses (of the various hosts connected to Switch B) against its single Port to forward relevant messages
Wireless Access Point
A Wireless Access Point is used to extend the Local Area Network to be accessible over Wi-Fi.
A WAP device can connect to the router to via a wired network
Router
A Router is used to route packets between networks using IP Addresses. It is a Layer 3 device.
It uses various routing protocols such as Distance Vector Protocols, Link State protocols to decide where to forward a packet
Firewall
A Firewall prevents unwanted network traffic from accessing your network and vice-versa.
Firewalls can either be network device or software on a computer ie. either network based or host based
DHCP server
A DHCP server or Dynamic Host Configuration Protocol is used to assign IP addresses dynamically to hosts within a network.
In addition to the IP Address, DHCP servers also provide the subnet mask, and the address for the default gateway when configuring a host connecting to the LAN
SOHO Device
A Small Office Home Office device is the wireless router at home. It combines a number of functionalities such as
- Router - Acts as default gateway connecting to the Internet
- Firewall - To secure the LAN from unwanted network traffic
- Switch - To provide communication within LAN
- Wireless Access Point - To provide network connectivity over WiFi
- DHCP server - To assign dynamic IPs to devices on LAN